In various applications such as automobile parts, cases of home electric appliances, furniture, office automation apparatus parts, and the like, there are wide demands for steel plates which are lightweight, highly rigid and shock resistant, and excel in workability for shearing, bending, deep-drawing, extending, and the like, as well as shape stability after being processed. In recent years, as measures for global warming, emissions of CO2 are strictly regulated. In the application of automobile parts in particular, to reduce the emission of CO2, high-level performance is particularly demanded not only for weight reduction but for rigidity and shock resistance, workability and shape stability after being processed. As solutions for such demands, various laminated steel plates are proposed in which a core layer formed of a resin sheet, a resin sheet with inorganic filler, a processed metal plate, a honeycomb, a fiber, and/or the like is laminated between steel plates.
However, laminated steel plates which have been proposed so far have not combined light-weightness, high rigidity, high shock resistance, excellent workability (shearing workability, bending workability, deep-drawing workability, extending workability, and the like), and excellent shape stability after being processed, and the like.